- Data ONTAP 8
- ONTAP 9
- An initiator sets a reservation on a LUN in order to prevent another initiator from making changes to the LUN, similar to a 'file-locking' concept.
- SCSI reservations are always set by a host initiator, and ideally, the same initiator performs a SCSI release on the LUN in use.
- Most LUNs are mapped to a single host, but in the case of a host cluster (e.g. VMware, SQL, Oracle), the same LUNs are mapped to multiple host nodes.
- In some cases, it might be necessary for the host to clear a reservation that it did not initiate.
- This is performed by running the 'lun reset' and 'target reset' SCSI commands.
Do you have to use a specific LUN when running the 'target reset' command?
The 'target reset' command can be run by an initiator without addressing a specific LUN, but a 'lun reset' command requires a specific LUN to be addressed.
Will a SCSI 'lun reset' command clear a SCSI-2 reservation?
Can a SCSI 'lun reset' command be run from any initiator, on any host, that has visibility to the LUN?
Yes, but the 'lun reset' command needs to be addressed to a specific LUN.
Will a SCSI 'lun reset' command affect any other initiators that are logged into a specific LUN?
Yes, all initiators mapped to a specific LUN will receive a LUN RESET notification.
Will a SCSI ' target reset' command affect all LUNs, from all initiators, that are logged into a target LUN?
The 'target reset' command on a NetApp SCSI target resets only those LUNs that are mapped to the initiator that is running.
Will a SCSI 'target reset' command clear SCSI-2 reservations on a mapped LUN that resides on a target?
Yes (see previous question). A SCSI-2 reservation will be cleared only on those LUNs that are reset.
Will a 'lun reset' or 'target reset' command affect SCSI-3 reservations?